High-clearance sprayers are getting larger and more complex to allow for increasing coverage in a single pass. Such sprayers oftentimes include operator comfort improvements like Heating, Ventilation and Air Conditioning (HVAC) systems to reduce operator stress and fatigue during long application sessions. Such HVAC systems can be designed to draw ambient air external to the operator cab, filter dust and/or other airborne materials from such air, and provide the air to the operator cab. However, these HVAC systems typically operate continuously while the machine is running, regardless of the state of the machine. As a result, if there is an opening the operator cab, the system may operate excessively, thereby shortening the life of the system. A need therefore exists for an improved system which eliminates one or more of the foregoing disadvantages.